Method of manufacture of cast valve rocker arms



Jan. 26, 1965 KQLBE 3,166,835

METHOD OF MANUFACTURE OF CAST VALVE ROCKER ARMS Filed Sept. 6, 1962 d IINVENTOR.

W BY flawed ewe &5 3 gwam ATTORNE Y United States Patent M 3,166,335METHUIB GE MANUFATURE 0F CAST VALVE RGCKER ARMS Adelbert E. Kolhe,Eerlriey, Mich, assigncr to General Motors Corporation, Detroit, Mich, acorporation of Delaware Filed Sept. 6, 1962, Ser. No. 221,8-34- 1illaim. (Cl. 29--414} This invention relates to rocker arms for internalcombustion engines and more particularly to an economical method ofmanufacturing them.

Heretofore, it has been common practice to form such rocker armsindividually out of forgings, castings, or sheet metal stampings. Thesequence of manufacture of rocker arms was performed such that eachforming operation was enacted on each rocker arm individually.Therefore, rocker arms were made one at a time.

It is an object of this invention to provide a method of manufacturingrocker arms in groups whereby certain operations can be madesimultaneously on the arms as a group.

In its broadest aspect, the invention provides a method in which aplurality of rocker arms are cast in one work piece and thereafter someof the ensuing finishing operations are performed simultaneously on eachconnected rocker arm.

In the drawings:

FIGURE 1 is a top view showing the cast work piece consisting of aplurality of rocker arms;

FIGURE 2 is a top view showing the sizing operation in which the bearingsurfaces of the connected rocker arms are formed to finished dimension;

FIGURE 3 is a side view of the work piece showing the forming operationin which all valve engaging surfaces and all push rod actuator engagingsurfaces of the connected rocker arms are coined to finished dimension;and

FIGURE 4 is a top view showing the final finishing operation in whichthe individual rocker arms are cut from the parent work piece casting.

Referring now to the drawings, there is shown in FIG- URE l a work piece10 which is cast in the shape of a plurality of conventionally shapedrocker arms 12 which are integrally connected together at their rockerarm bearing bosses 14. Each rocker arm 12 has the usual valve engagingend 16 and the usual push rod engaging end 18.

The rocker arms 12 of the work piece 10 are cast to size as well as canbe done, however, certain areas must be precisely finished. Referring toFIGURE 3, there is shown a forming press having an upper die block 20and a lower die block 22. The lower die block 22 has a plurality ofaligned pins 24 and a plurality of aligned sockets 26. The work piece 10is placed in the lower die block so that each of the rocker arm ends 18rests on one of the aligned pins 24, and so that each of the rocker armends 16 rests in one of the aligned sockets 26. The upper 3,l6fi,35Patented Jan. 26, 1965 die block 20 carries projections 28 and 30 whichbear on the upper surfaces of the rocker arm ends when the press isclosed to thereby coin a finished push rod engaging surface 32 and afinished valve stem engaging surface 34 in each of the connected rockerarms 12.

The Work piece 10 may be cast with an unfinished bore for the rocker armshaft, or the rocker arm bosses 14 may be cast solid. In either case, itis necessary to size the rocker arm shaft bore and this is done to theconnected rocker arms 12 by suitable means, such as a drill 36, as maybe seen in FIGURE 2. The drill 36 is advanced through the rocker armshaft bosses 14 to provide a shaft bearing bore 38. The shaft bearingbore 38 can then be reamed to attain the tolerances and surfaceconditions required. The finished surfaces 32 and 34 of the work piece10 can serve as locating pads to mount the work piece 10 for properalignment during the drilling and finishing operations such that theshaft bearing 38 in each of the rocker arms is uniform.

Following the drilling operation, any other operations which may bedesired, such as drilling oil holes in the rocker arms, can beaccomplished in a unified manner on the work piece 10. Following this,the work piece 10 is thereafter cut up into individual rocker arms 12 bymeans of a saw or milling cutter 40, as shown in FIGURE 4. Only onecutter is shown in FIGURE 4 but it is obvious that a plurality ofcutters may be employed if desired to simultaneously separate the workpiece 10 into the individual rocker arms 12.

While the invention is described with respect to specific steps ofoperation and finishing, some variances from that exactly described maybe made and still fall within the scope of the claim which follows.

I claim:

A method of manufacturing internal combustion engine rocker arms of thetype having a bore for a shaft bearing, a push rod engaging surfaceoffset from said bore, and a valve engaging surface offset from saidbore and from said push rod engaging surface comprising the steps of:

casting a work piece in the shape of a plurality of connected rockerarms aligned with respect to the axis of said bore and with saidsurfaces aligned from end to end of said work piece;

simultaneously coining the push rod engaging and the valve engagingsurfaces of the plurality of rocker arms; forming and finishing theshaft bearing bore of said rocker arms by drilling and reaming alongsaid axis;

and subsequently severing each individual rocker arm from the remainderof said rocker arms constituting said work piece.

References Qited in the file of this patent UNITED STATES PATENTS1,784,866 Fahrenwald Dec. 16, 1930 2,156,692 Hixon May 2, 1939 2,510,091Dofsen et al. June 6, 1950 2,759,257 Schlegel Aug. 21, 1956

